Present-day sequential display systems typically comprise a light source that illuminates a light modulator that has the capability of controlling the illumination of each of a plurality of picture elements (pixels) projected onto a display. A controller controls the light modulator in response to an input television signal so that the light modulator will display successive pictures in the television signal, each picture appearing during a corresponding picture interval. The length of the picture interval depends on the selected television standard. The NTSC standard currently in use in the United States prescribes a picture interval of 1/60 second whereas certain European television standards (e.g., PAL) prescribe a picture interval of 1/50 second.
A typical sequential display system achieves a color display by sequentially projecting red, green, and blue light onto the light modulator during each picture interval. Many sequential display systems utilize a motor-driven color wheel interposed in the light path of the light modulator to accomplish this task. The color wheel has at least one set of primary color windows (typically red, green and blue) so that upon rotation of the color wheel, red, green, and blue light illuminate the light modulator. (Most present day color wheels have multiple sets of primary color windows.) In practice, each color is broken up into an integer number of segments, with the segments of each color interleaved with the segments of the other colors in time, thereby shortening the interval between colors to reduce the problem of color break up with motion.
Separating the picture into sets of primary color segments usually incurs the disadvantage that a moving white object will suffer color distortion (i.e., motion artifacts) at its leading and trailing edges. In each new picture, the leading edge will have the same primary color say red, while the trailing edge will always have another primary color, say green, as the preceding picture. Usually, this problem is slightly reduced but not eliminated, by increasing the number of primary color segments per picture to minimize the visibility of the colors at the leading and trailing edges of the object. However, most sequential display systems limit the number of primary color segments per picture.
Thus, there is need for a technique for minimizing such motion artifacts in a sequential display system.